Switching Power Supply Feedback Correction for Cable Voltage Drop
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Solution Overview
Problem
Switching power supply apparatuses struggle to maintain a stabilized output voltage across cables due to voltage drops caused by cable impedance, which worsens with increasing load, despite existing solutions that can manage sudden load changes.
Innovation Solution
A switching power supply apparatus with a transformer, a switching element, an output circuit, and a feedback signal generation circuit that corrects the signal level based on the secondary side conduction period to compensate for voltage drops, using a voltage divider circuit with a CR serial circuit to adjust the feedback signal level and maintain stable output voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching power supply apparatus uses conventional feedback control to suppress sudden load changes, then the output voltage stability at the power supply device is improved, but the voltage drop at the cable output cannot be suppressed due to cable impedance
Solution Approach 1:
The patent applies preliminary action by predicting the voltage drop at the cable output before it occurs. The prediction unit calculates the expected voltage drop based on the relationship between output current and cable impedance, then the feedback control unit preemptively adjusts the output voltage to compensate for this predicted drop, ensuring stable voltage at the load end before the drop actually manifests
Solution Approach 2:
The patent implements feedback by introducing a prediction unit that continuously monitors output current and calculates the resulting voltage drop across the cable. This predicted voltage drop information is fed back to the control unit, which adjusts the output voltage accordingly. This closed-loop feedback mechanism enables the system to counteract cable impedance effects dynamically
2Reliability
If the output voltage is increased to compensate for cable voltage drop, then the voltage at the load end is stabilized, but the voltage fluctuation at the power supply device output increases
Solution Approach 1:
The system performs preliminary calculation of the required voltage compensation based on predicted output current and cable impedance characteristics. By pre-determining the exact compensation amount needed, the system avoids excessive or insufficient adjustment, thereby stabilizing the load end voltage while minimizing unnecessary fluctuations at the power supply output
Solution Approach 2:
The patent dynamically changes the output voltage parameter based on the predicted load conditions and cable characteristics. The control unit adjusts the voltage magnitude precisely according to the calculated voltage drop, transforming the system from a fixed voltage output to a dynamically adaptive voltage output that compensates for cable effects without causing excessive fluctuation
3Reliability
If a complex control circuit is used to compensate for cable voltage drop, then the voltage stabilization performance is improved, but the device complexity increases
Solution Approach 1:
The patent uses feedback by implementing a prediction unit that leverages existing output current detection capabilities and stored cable impedance data. This approach reuses existing system resources rather than introducing entirely new sensing mechanisms, achieving voltage drop compensation through intelligent processing of available information while maintaining relatively simple circuit architecture
Solution Approach 2:
The system applies self-service by utilizing its own output current detection capability and internal processing units to calculate and compensate for voltage drops. The existing microcontroller or control logic performs the prediction and adjustment functions using already-available electrical parameters, eliminating the need for additional external sensors or complex dedicated hardware circuits
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively stabilizes the output voltage across cables regardless of load changes, compensating for voltage drops and maintaining consistent power delivery to loads, without requiring modifications to the control circuit or additional components beyond a simple feedback signal correction.
Implementation Method 1
a transformer having a primary winding, a secondary winding, and an auxiliary winding; power being transferred from the primary winding to the secondary winding in response to a switching operation of the switching element
Implementation Method 2
an auxiliary winding, to which a voltage proportional to a voltage generated to a secondary winding of the transformer is induced
Data Source
AI summary
A switching power supply apparatus includes a transformer having a primary winding, a secondary winding, and an auxiliary winding, a switching element coupled in series to the primary winding; an output circuit section generating a voltage output from power transferred from the primary winding to the secondary winding in response to a switching operation of the switching element, a feedback signal generation circuit section configured to, during a secondary side conduction period in which an electric current flows through the secondary winding, generate a feedback signal having a signal level corrected based on a length of the secondary side conduction period, from an auxiliary winding voltage induced in the auxiliary winding, and a control circuit section driving the switching element based on the feedback signal.